Producing anti-fibrinolytic activity with aminobicycloacetic acid derivatives

ABSTRACT

THE COMPOUND 4-EMINOMETHYLBICYCLO-(2.2.2)-OCTANE-1ACETIC ACID AND THE PHARMACEUTICALLY ACCEPTABLE SALTS THEREOF ARE USEFUL AS ANTI-FIBRINOLYTIC COMPOUNDS.

United States Patent 3,743,742 PRODUCING ANTl-FIBRINOLYTIC ACTIVITY WITHAMINOBICYCLOACETIC ACID DE- RIVATIVES Larry J. Loefiler, North Wales,Pa., assignor to Merck & Co., Inc., Rahway, NJ.

No Drawing. Original application June 17, 1969, Ser. No. 834,139, nowPatent No. 3,641,129. Divided and this application June 25, 1972, Ser.No. 157,036

Int. Cl. A61k 27/00 US. Cl. 424-319 2 Claims ABSTRACT OF THE DISCLOSUREThe compound 4-aminomethylbicyclo-[2.2.2]-octane-1- acetic acid and thepharmaceutically acceptable salts thereof are useful asanti-fibrinolytic compounds.

This application is a division of US. Ser. No. 834,139, filed June 17,1969, now US. Pat. 3,641,129.

This invention relates to a new anti-fibrinolytic compound and to amethod of counteracting certain hemorrhagic conditions and otherdisorders resulting from a pathological fibrinolytic state in patients.More specifically, this invention relates to a new compound of thestructure umom-omooon and the pharmaceutically acceptable salts thereof.More specifically, it relates to the prevention or treatment of apathological fibrinolytic state in patients by the oral administrationof from 1 to 20 preferably 2 to 8 mg./kg. of body weight per day of theabove compounds for varying periods of treatment.

The dissolution of fibrin deposits in mammals is due to their lysis bythe enzyme plasmin (fibrinolysin) which is formed in the blood fromplasminogen, also present in the blood. This conversion from plasminogento plasmin is promoted by activators in the blood and it would appearthat excessive fibrinolytic activity results from an over-abundance ofsuch activators. When too much plasmin is present, the clotting systemof the blood becomes unbalanced, viable clots cannot be maintained, andhemorrhage may result. This situation is known as a fibrinolytic state.Other enzyme systems (i.e., the kallikreins, complement) may also beactivated in an undesirable manner when such a state exists.

An interest has recently developed in anti-fibrinolytic agents, i.e.drugs which will inhibit the activation of plasminogen to form plasmin.These anti-fibrinolytic agents are believed to interfere with thefunction of the activators of converting plasminogen to plasmin. Theclinical uses of such drugs include their administration to personsundergoing various kinds of surgery (such as heart-lung and prostatesurgery), obstetrical hemorrhage problems, menorrhagia, and many otheruses which have been suggester in the literature (e.g. see Nilssen, ActaMedica Scand. Suppl. 448, volume 180, 1966).

A standard anti-fibrinolytic agent, against which newer ones aregenerally tested and compared is epsilon aminocaproic acid, known asEACA. One deficiency of this agent has been the very high dosagesneeded; in some cases 3-6 grams or more every 4 to 6 hours. Also, sideeffects such as dizziness, nausea and diarrhea have been observed. Morerecently, two more potent agents have been described, namelytrans-4-aminomethylcyclohexane carboxylic acid (AMCHA) and4-aminomethylbenzoic acid (PAMBA). Each is reported to be more activethan EACA by both in vitro and in vivo tests (e.g. see Anderssen et al.Scand. J. Haemat. (1965) 2, 230 and 3,743,742 Patented July 3, 1973 ICCMelander et al. Acta Pharmacol. et Toxicol 22, 340 (1965), both of whichdiscuss AMCHA).

I have found a new aminomethyl bicyclic carboxylic acid which shows anactivity of 10 times that of EACA in tests essentially the same as thoseknown to correlate with clinical results. I have thus also found animproved anti-fibrinolytic method of therapeutic treatment requiringmuch smaller doses of the drug.

The new compound of my invention has the general structurenmom-Q-ornooon The pharmaceutically acceptable salts of the compoundalso show anti-fibrinolytic activity.

The present invention also provides a process of preparing a compound ofthe structure nmom-@-ornooon which comprises hydrolyzing a compound ofthe structure wherein R is an organic radical containing of from 1 toabout 10 carbon atoms. The hydrolysis is carried out under conventionalconditions generally in the presence of an inorganic acid. In apreferred embodiment of the present invention, the R groups are eitherlower alkyl or benzyl.

The compound is used in the method of this invention by either oral orintravenous administration, although the oral route is preferred. Theesters and amides of this class compound are not themselves very activein vitro but the action of enzymes in vivo causes the slow liberation ofthe highly active amino acids, thus providing a prolonged availabilityof the drug in the body. This is important because of the tendency ofthese drugs to be swiftly eliminated in the urine. Such amides andesters are to be considered as being within the scope of the presentinvention since it is actually the present compound which produces theresults within the body.

The compound of this invention can be used in a composition comprisingan pharmaceutically acceptable carrier, in the form of pills, tablets orcapsules. The pharmaceutically acceptable salts (both of the amino groupsuch as the hydrochloride, hydrobromide, sulfate, citrate, tartrate,etc.-and of the carboxy groupsuch as the alkali metal, alkaline earthmetal, etc., salts) are readily usable, especially in injectablecompositions.

The invention can be illustrated by the following examples.

EXAMPLE 1 (A) 4-aminomethylbicyclo-[2.2.2]-octane-1-carboxylic acidhydrochloride salt To a solution of 2.80 g. (0.0156 mole) of4-cyanobicyclo-[2.2.2]-octane-1-carboxylic acid (Roberts et al., JACS,1953, 75, 637) in 100 ml. ethanol is added 5.0 ml. 6 N hydrochloric acidand 500 mg. platinum oxide. During hydrogenation on a Parr apparatus atroom temperature and 40 lbs/in. pressure, the theoretical quantity ofhydrogen is absorbed during the first half hour. After 2 hours, thehydrogenation is stopped and the reaction mixture filtered throughsintered glass to remove the platinum catalyst. Evaporation of theclear, colorless filtrate in vacuo (30-40 C.) leaves a white solid whichis reevaporated with three portions of ethanol to remove most of theexcess hydrochloric acid. Purification is accomplished by dissolution in200 ml. hot ethanol and reprecipitation with 750 ml. absolute ethylether. The

white solid, M.P. 31=8-319 C. dec. (placed in sealed capillary at 250C.) after air drying, is obtained in 90.5% yield. Threerecrystallizations from 95% ethanol ether gives analytically purematerial, M.P. 318-319" C. dec., which is dried at 110 C. overphosphorous pentoxide for 18 hours at 0.08 mm. Hg. The product exhibitsa single circular ninhydrin positive spot (pink) upon thin layerchromatography on silica gel with 3:1:1 n-butanol, acetic acid water,R;=0.65.

(B) 4-benzamidomethylbicyclo-[2.2.2]-octane-1- carboxylic acid (C)4-benzamidomethylbicyclo-[2.2.2]-octane-lcarboxylic acid chloride To asuspension of 3.38 g. (0.012 mole)4-benzamidomethylbicyclo-[2.2.2]-octane-1-carboxylic acid in 10 ml.benzene is added 30 ml. thionyl chloride. The mixture is heated toreflux for 4 hours. After removal of the excess benzene and thionylchloride in vacuo, the solid acid chloride is reevaporated several timeswith fresh benzene, then pumped in high vacuum over P The solid productis used for reaction with diazomethane without further purification.

(D) 4-benzamidomethylbicyclo--[2.2.2]-octane-1- (3-diazo)-acetone To asolution of 0.036 mole of diazomethane in 150 ml. ether at 0 to 5 C. isadded over 2 hours a solution of the acid chloride prepared above. Thesolution is allowed to evaporate in a stream of dry nitrogen overnight.The resulting oily solid shows an intense band in the infrared at about2100 cm.- (diazo) and is free of the acid chloride absorption at 1725cm.-

(E) 4-benzamidomethylbicyclo- [2.2.2] -octane-1- acetic acid Arearrangement is accomplished by the addition of small portions of thediazoketone (3.10 g., 0.010 mole) to 12 ml. of a mixture of collidineand benzyl alcohol at 170180 C. over a 5-10 minute period. After theaddition of ether to the cooled mixture, it is extracted thoroughly with3 N hydrochloric acid, then water, and finally dried over magnesiumsulfate. After filtration and removal of the ether in vacuo, the excessbenzyl alcohol is removed by distillation (75/2 mm. Hg). This crudebenzyl ester (3.35 g.) is saponified by stirring overnight in 12 ml.ethanol containing 4.3 ml. 2.0 N NAOH. Removal of the ethanol andacidification of the aqueous solution gives an oil which is extractedinto ethyl acetate. The oil is purified by column chromatography onsilica gel (benzenethyl acetate eluant) to give pure4-benzamidomethylbicyclo-[2.2.2]-octane-1-acetic acid (700 mg. 23%yield). Because this material could not be obtained in crystalline form,it is hydrolyzed directly without further purification to the aminoacid.

(F) 4-aminomethylbicyclo- [2.2.2] -octane-l-acetic acid hydrochloride To700 mg. (2.3 mmoles) of amido acid is added 20 ml. concentratedhydrochloric acid and 20 ml. glacial acetic acid and the mixture isrefluxed overnight. After removal of the solvents in vacuo, 50 ml. ofwater is added and the solution extracted thoroughly with ether.Evaporation of the aqueous layer leaves a white solid, M.P. 254-260 C.dec. (yield 388 mg., 72% Recrystallization from ethanol-ether givesanalytically pure material, M.P. 256.5260 C. dec., after drying in highvacuum at C.

EXAMPLE 2 The compound is tested in vitro by measuring the elfect of theinhibitor at various concentrations on the lysis times of a fibrin clotwith a constant concentration of streptokinase in plasminogen-richplasma. The concentration of the inhibitor which increases the geometricmean lysis time by 50% is estimated. Epsilon amino caproic acid (EACA)is used as a standard and the relative potencies are obtained, with thefollowing results:

Relative in vitro activity Compound: (weight basis) (A) Referencecompound: EACA 1.0

(B) New compound: 4 aminomethylbicyclo- [2.2.2]-octane-1-acetic acid 10Many other equivalent modifications of the invention would be apparentto those skilled in the art from a reading of the foregoing without adeparture from the inventive concept.

I claim:

1. A method of producing anti-fibrinolytic activity and treatinghemorrhagic conditions in patients with a pathological fibrinolyticstate which comprises the intravenous or oral administration of from 1to 20 mg./kg. per day of a compound of the structure and thepharmaceutically acceptable salts thereof.

2. The method of claim 1 in which said daily administration is from 2 to8 mg./kg. of body weight.

References Cited Miyamoto et al., Chem. Abst., vol. 57 (1962), p.17313a.

SAM ROSEN, Primary Examiner

